Method of applying metallic stripes to a web of paper



E. l. BARTH Feb. 22, 1955 METHOD OF APPLYING METALLIC STRIPES TO A WEBOF PAPER Filed April 25, 19 51 [III [/11 ll IIIlIIIlI/l/lll'l l1 1[11/11 1111 1/ V LII/[[1 111111111 [If 1/17/1111 I lllllll \llll U /J 9a lvllll United States latent O METHOD or APPLYING MET LLIC STRIPES 'roA WEB OF PAPER Application April 25, 1951, Serial No. 222,855

8 Claims. (Cl. 117-38) This invention relates to methods of andapparatus for coating articles, and more particularly to methods of andapparatus for sputtering metal coatings on elongated strips ofinsulating material.

In the manufacture of stripsof paper having a plurality of stripes orhands of metal extending along one face thereof and separated from eachadjacent band for use in making condensers, it has been very difiicultto apply such bands of uniform thickness from edge to edge of each band.It has been proposed, in the past to completely mask each portion of thestrip separating the bands. However, when this is done, heavier depositsof metal have been built up at the edgesof the stripes than at thecentral portions of the stripes, particularly when the portions to bestriped have seeding particles thereon to facilitate precipitation ofthe primary coating metal.

An object of the invention is to provide new and 1mproved methods of andapparatus for coating articles.

Another object of the invention is to provide new and improved methodsof and apparatus for applying stripes of metal coatings to elongatedstrips of insulating material.

A further object of the invention is to provide methods of and apparatusfor forcing finely divided metal particies toward a strip whiledifferentially masking the strip to form bands uniform in thickness fromedge to edge.

In a method illustrating certain features of the invention, a strip ofinsulating material having seeded bands separated by uncoated stripes isadvanced past a metal vaporizer, and theportion of the strip passing thevaporizer is masked differentially less proceeding from theuncoatedportions toward the central portions of the A complete understanding ofthe invention may be obtained from the following detailed description ofa method and an apparatus forming specific embodiments thereof, whenread in conjunction with the appended drawings, in which Fig. 1 is avertical section of an apparatus for practicing a method forming aspecific embodiment of the invention;

Fig. 2 is a horizontal section taken along line 2-2 of Fi 1, an

iig. 3 is a perspective view of a portion of the apparatus shown in Fig.l.

Referring now in detail to the drawings, there is shown therein anapparatus for applying stripes or hands -10 of metal to a web or strip11 of insulating material, such as, for example, thin paper coatedwithin cellulose acetate butyrate on the face to be metallized, to formcomponents of condensers. The strip 11is advanced continuously from asupply roll 12 mounted in a chamber 14, the interior of which is kept ata very low absolute pressure of from 0.25 to 0.5 millimeter of mercury.The paper is taken up on a takeup roll 16 and is advanced continuouslyover a seeding applicator 17 and a metallizing applicator 18. Theapplicator 17 includes a heated cham-- ber 20, which has a supply of aseeding metal 21 therein heated to the point of vaporization. Thevaporrzedseeding metal, which may be silver, nickel, copper or the like,passes through openings 22-22 formed in a nozzle 23 and separated bysolid masking strips 24-24 to form very thin seeding bands 25-25 on thestrip, which are the same width as the bands 10-10.

The striped paper passes from the applicator 17 over a noule 30 of themetallizing apphcator 18, which mcludes a heated chamber 31 having asupply of molten 2,702,760 Patented Feb. 22, 1955 metal 32, such aszinc, aluminum or other suitable sputtertng metals. The metal ismaintained at or near the boiling temperature thereof so that the metalis volatihzed and projected toward the nozzle 30 continuously. Thenozzle 30 has an orifice 35 therein, which tapers from wide at theportions thereof over which the central portions of the bands 25-25 passto narrow at portions thereof over which uncoated stripes 36-36 anduncoated edges 38-38 of the strip pass. Opposed pairs of intersectingarcs 39-39 form the orifice 35. Consequently, the outer edges of thebands 25-25 and the uncoated stripes 36-36 are masked greater than thecentral portions of each of these bands. However, the vaporized metal 32projected through the orifice 35 moves from the spaces aligned with theuncoated stripes 36-36 into the edge portions of the seeded bands 25-25.The proportions of the exposed areas of the edge portions of the bands25-25 relative to the exposed areas of the central portions of the bands25-25 are such that the thickness of the metal precipitated on the bandsis uniform in thickness from edge to edge. The strip 11 is advanced overthe applicator 18 suificiently rapidly that the metal projected throughthe nozzle 30 coats only the seeded bands 25-25, does not adhere to theuncoated stripes 36-36 or uncoated edge portions 38-38 of the strip 11,and damage to the strip 11 from heat of the applicators and thevolatilized metal is prevented.

, A strip of paper and cellulose acetate butyrate forming the surface tobe coated was advanced over the applicators l7 and 18 continuously at arate of speed of about 1500 feet per minute. The combined thickness ofthe paper and the cellulose acetate butyrate was in the order of 0.0003inch. The interior of the chamber 14 was maintained underabsolute'pressure of 0.1 millimeter of mercury, and zinc in theapplicator 18 was maintained at a temperature of about 1100" F. Silverin the applicator 17 was maintained at a temperature of approximately1750 F. Silver was applied uniformly to the ous, smooth, dense depositsof uniform thickness across the entire widths of the bands 25-25. Thethickness of each of the bands 10-10 form one edge thereof to theopposite edge thereof and along the entire length of the strip wasuniform, and there were sharp lines of demarcation at the edges of thebands between the metallized portions and the uncoated separatingstripes 36-36 and edge portions 38-38 of the strip 11.

A lacquered strip of paper was advanced over the applicators 17 and 18at a rate of speed of about 1500 feet per minute. The chamber 14 wasmaintained under an absolute pressure of about 0.1 millimeter ofmercury, and aluminum in the applicator 18 was kept at a vaporizationtemperature. Silver in the applicator was kept at its vaporizationtemperature for the pressure of the chamber 14. Smooth, dense,fine-grained bands of aluminum uniform in thickness from edge to edgewere formed and sputtered onto the strip through the nozzle with theunseeded portions on the strip kept entirely free of metal.

The nozzle 18 used in the above-described examples had an orifice 9%inches long in transverse cross-section and at the widest points thereofwas -78 inch wide, while at the narrowest points thereof was inch wide.The orifice was formed by three pairs of opposed arcs of a radius of19%,; inches. The bands 10-10 formed by the nozzle were 2.692 incheswide and were separated by uncoated stripes 36-36 0.326 inch in width.The thickness of the metal plate in which the orifice was formed was0.062 inch, and the nozzle was composed of type 300 stainless steel.

It is to be understood that the above-described arrangements are simplyillustrative of the application of the principles of the invention.Numerous other arrangements may be readily devised by those skilled inthe art which will embody the principles of the invention and fallwithin the spirit and scope thereof.

What is claimed is:

1. The method of coating articles, which comprises advancing a strip ofmaterial having very thin seeded bands of a metal of the groupconsisting of silver, copper and nickel separated by unseeded stripesextending therealong continuously along a predetermined path, directinga vaporized coating of a metal of the group consisting of zinc andaluminum toward the strip at one portion of the path, and simultaneouslymasking all the strips atsaid portion of the path except a band acrosssaid portion that is narrow at the unseeded stripes and increases inwidth from the stripes toward the central portions of the seeded bands,whereby the second metal coats the bands uniformly from edge to edgewithout greater thickness at the edges.

2. The method of forming metallized strips of paper, which comprisesadvancing a strip of paper along a predetermined path, continuouslyapplying vaporized silver at one point in said path to portions of thestrip spaced laterally from one another to form very thin seeded bandson the strip spaced apart by uncoated stripes, directing vaporized zinctoward the strip at a subsequent point in the path, and simultaneouslymasking the strip incrementally less at said point from the uncoatedstripes toward the centers of the seeded bands, whereby such difierencein masking overcomes any tendency of the zinc to be deposited morequickly at the edges of the band and results in a uniform thickness ofcoating across the width of the bands.

3. The method of making metallized paper, which comprises continuouslyadvancing a strip of paper over a silver chamber and a zinc chamber,continuously directing vaporized silver in the silver chamber at thestrip to coat the strip very thinly, completely masking laterally spacedportions of the portion of the strip being advanced over the silverchamber to form uncoated stn'pes separating the coated portions,directing vaporized zinc in the zinc chamber toward the strip to coatthe strip, continuously exposing substantially the entire width of Y thestrip to the vaporized zinc with the length of exposure of the strip tothe vaporized zinc being a minimum at the uncoated stripes andincreasing toward the center of each coated portion, whereby thickerdeposits of zinc at the edges of coated portions are prevented and thezinc is deposited in uniform thickness across the coated portions.

4. The method of applying zinc to strips of paper, which comprisesadvancing a strip of paper having. very thin silver bands separated byunmetallized stripes extending therealong continuously along apredetermined path, directing vaporized zinc toward the strip at oneportion of the path, and simultaneously masking all the strip at saidportion of the path except a band across said portion that is narrow atthe unmetallized stripes and increases in width from the stripes towardthe central portions of the silvered bands, whereby the zinc coats thebands uniformly from edge to edge and thicker deposits at the edges ofthe bands are prevented.

The method of forming metallized strips of paper, which comprisescontinuously advancing a strip of paper along a predetermined path,creating low pressure around said path, continuously directing vaporizedsilver to portions of the strip spaced laterally from one another at onepoint in said path to form very thin seeded bands -on the strip spacedapart by uncoated stripes, vaporizing and directing zinc toward thestrip at a subsequent point in the path, and continuously masking thestrip incrementally less at said second point from the uncoated bandstoward the centers 'of the seeded bands, whereby thickened edge portionsof zinc are prevented and the zinc is deposited in layers uniform inthickness from edge to edge of each layer.

thin seeded bands on the strip spaced apart by uncoated strips,continuously projecting vaporized zinc toward the face of the strip at asubsequent point in the path, and

continuously masking the strip at said second point incrementally lessfrom the uncoated stripes toward the centers of the seeded bands,whereby the zinc is deposited with uniform thickness from edge to edgeof the seeded bands.

7. The method of metallizing strips, which comprises continuouslyadvancing a strip of insulating material along a predetermined path in apredetermined direction, maintaining the space surrounding said path ina high vacuum, continuously directing toward the strip at one point inthe path a vaporized metal of the group consisting of silver, nickel andcopper adherent with respect to the strip at such a rate of depositionas to form an imperceptibly thin deposit of the metal of a thickness inthe order of one molecular layer on the strip to form a band thereon,continuously directing toward the strip at a subsequent point in thepath a second vaporized metal of the group consisting of zinc andaluminum adherent to the first metal, and simultaneously partiallymasking the portion of the strip continuously at said second pointincrementally less from the edges of the band ing overcomes any tendencyof the coating of the second metal to be thicker at the edges and is ofuniform thickness acres the width of the band.

8'. The method of metallizing strips, which comprises continuouslyadvancing a strip of insulating material along a predetermined path in apredetermined direction, maintaining the space surrounding said path ina high vacuum, continuously directing toward the strip at one point inthe path vaporized silver at such a rate of deposition as to form animperceptibly thin deposit of the silver on the strip to form a bandthereon of a thickness in the order of one molecular layer, continuouslydirecting zinc toward the strip at a subsequent point in the path, andsimultaneously partially masking the portion of the strip from the edgesof the .band toward the center of the band to deposit the zinc uniformlyon the band to prevent thicker deposits of the zinc at the edges of theband and cause the deposits of'zinc to be uniform in thickness from edgeto edge of the band.

References Cited in the tile of this patent 1 UNITED ATES PATENTSMelsheimer Mar. 25, 1952

1. THE METHOD OF COATING ARTICLES, WHICH COMPRISES ADVANCING A STRIP OFMATERIAL HAVING VERY THIN SEEDED BANDS OF A METAL OF THE GROUPCONSISTING OF SILVER, COPPER AND NICKEL SEPARATED BY UNSEEDED STRIPESEXTENDING THEREALONG CONTINUOUSLY ALONG A PREDETERMINED PATH, DIRECTINGA VAPORIZED COATING OF A METAL OF THE GROUP CONSISTING OF ZINC ANDALUMINUM TOWARD THE STRIP AT ONE PORTION OF THE PATH, AND SIMULTANEOUSLYMASKING ALL THE STRIPS AT SAID PORTION OF THE PATH EXCEPT A BAND ACROSSSAID PORTION THAT IS NARROW AT THE UNSEEDED STRIPES AND INCREASES INWIDTH FROM THE STRIPES TOWARD THE CENTRAL PORTIONS OF THE SEEDED BANDS,WHEREBY THE SECOND METAL COATS THE BANDS UNIFORMLY FROM EDGE TO EDGEWITHOUT GREATER THICKNESS AT THE EDGES.